To the Editor.—Operating on the wrong patient, the wrong side of the patient, or the wrong body part is a rare but devastating error. Recent instances, widely publicized in the lay press, include amputating the wrong foot,1 performing mastectomy on the wrong breast,1 exploring the wrong cerebral hemisphere,2 and removing the wrong lung from a patient with carcinoma of the lung.3 Almost always these misadventures happen to patients who are fully draped and under general anesthesia, who cannot point out the mistake as it occurs. In a just-published analysis of the foot amputation error,4 the operating room schedule and the hospital computer listed the wrong operation, and the patient was indeed draped and asleep when the surgeon entered the operating room.I would like to suggest a method for preventing such errors. When a patient is evaluated prior to surgery, the attending surgeon should at